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A087544 a(0) = 1, a(1) = 3, a(n) = smallest prime beginning with the sum of two previous terms. 4

%I #11 Dec 10 2018 16:44:17

%S 1,3,41,443,48407,488503,5369101,585760421,59112952201,5969871262259,

%T 60289842144607,6625971340686661,66862611828312689,

%U 7348858316899935071,741572092872824776001,7489209511897247110721,82307816047700718867221

%N a(0) = 1, a(1) = 3, a(n) = smallest prime beginning with the sum of two previous terms.

%H Robert Israel, <a href="/A087544/b087544.txt">Table of n, a(n) for n = 0..322</a>

%e a(3) = 41, a(4) = 443, a(5) = 48407 is the smallest prime beginning with 41+443=484.

%p A[0]:= 1: A[1]:= 3:

%p for n from 2 to 20 do

%p s:= A[n-2]+A[n-1];

%p for d from 1 do

%p p:= nextprime(10^d*s);

%p if floor(p/10^d)=s then A[n]:= p; break fi

%p od

%p od:

%p seq(A[n],n=0..20); # _Robert Israel_, Dec 10 2018

%t a[0] = 1; a[1] = 3; a[n_] := a[n] = Module[{s = a[n - 1] + a[n - 2]}, Do[p = 10^d*s; While[! PrimeQ[p], p = NextPrime[p]]; If[Floor[p/10^d] == s, Break[]], {d, 1, 20}]; p]; Array[a, 10, 0] (* _Amiram Eldar_, Dec 10 2018 from the Maple code *)

%Y Cf. A087541, A087542, A087543.

%K base,nonn

%O 0,2

%A _Amarnath Murthy_, Sep 13 2003

%E More terms from _Ray Chandler_, Sep 23 2003

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Last modified April 24 12:31 EDT 2024. Contains 371937 sequences. (Running on oeis4.)